The present invention generally relates to a method for malting seeds, such as barley seeds and other cereals, such as wheat and sorghum seeds, legumes and pseudo-cereals. More particularly, the method includes reducing the microbial count of the seeds prior to malting and/or prior to adding a starter culture for the malting process.
Heat and moisture are applied onto the particulate seeds to provide a heated moist environment which provides surface moisture on the seeds during the application of heat. Heat is applied for a time and temperature sufficient to reduce the microbial load of the seeds or other malting seeds without affecting or minimally affecting, the loss of the ability of the seeds to germinate and undergo a malting process.
Barley and other seeds, such as wheat and sorghum, are used for the production of beverages, such as beer. In most cases, a seed is subjected to a malting process to increase enzymatic activity. These enzymes, such as amylases, betaglucanase and xylanase enzymes, degrade the starch and non starchy components from the seeds to prepare them to be used in processes such as brewing. In known malting processes, the moisture content of a seed, such as barley, is raised by immersion of the barley seeds in water. Thereafter, the barley with a high moisture content is allowed to germinate to provide a green malt. After germination, the green malt is dried under specific conditions. The final malt is cleaned to remove, for example, the sprouts and dust. Thereafter, it is used in processes, such as brewing, milling or other fermentation processes.
Barley and seeds contain naturally occurring microorganisms. Generally, the quality of the malt and the beverage derived therefrom can be affected by the presence of microorganisms naturally present on and in the barley and other seeds. Some microorganisms positively affect malting, some do not. Generally, these microorganisms are further developed and grown during the malting process. During microorganism growth, metabolites can be produced, some of which are known to negatively influence the quality of the final malt. For example, some molds such as Fusarium can produce vomitoxin (=deoxynivalenol, often referred to as DON). DON is a harmful mycotoxin and levels of that mycotoxin should be kept as low as possible. It is believed mold or yeast strains developed or grown during the germination process also produce proteins which are claimed to cause gushing in beer produced from that malt. Moreover, other products formed by microorganisms during germination can be polysaccharides which are believed to cause early flocculation of yeast during fermentation in the brewing of the malted seeds. Hence, many microorganisms adversely affect the malting process and/or adversely affect the quality of the beverage which is made from the seeds, such as barley.
Further, mycotoxins and/or other metabolites can be produced during the malting process. Indeed, malting process conditions from steeping to drying are such, that they encourage microbial growth and development and enhance the production of metabolites. And even though these metabolites originally present on the seed before the process generally are removed with the steep water after steeping, not all of the microorganisms and metabolites are removed. Moreover, after steeping and during the germination process and the first phase of the drying process, microorganisms can again develop and produce these metabolites.
A lower initial microbial count in seeds which undergo a malting process would not only reduce the level of undesirable microorganisms in the seeds, but also could prevent the production of metabolites of those microorganisms. A treatment lowering microbial count must be balanced so as not adversely affect the ability of the barley and other seeds to germinate, nor to destroy viable seed tissues critical to obtaining a good quality malted seeds. Hence, the embryo in the barley and other seeds should not be so adversely affected so that they will not be metabolically inactivated and will not germinate and produce, for example, enzymes as part of the malting process.
An object of the invention is to provide an improved preparation process for making malted seeds and to improve the malted seeds product of such process.
Another object of the invention is to provide a process and improved malted seed which vary less in quality with the raw material used.
Additional objects of the invention will become apparent with reference to this specification.
The invention provides a process or method of malting seeds selected from the group consisting of cereals, such as barley, wheat, rye, corn, oats, rice, millet and sorghum, pseudo-cereals, such as buckwheat, amaranth and legumes, such as soy. The process of the invention includes reducing the microbial level in the seed prior to steeping and malting and also can comprise the introduction of a starter culture used in the malting process. According to the invention, the reduction of microbial levels permits efficient use of starter cultures, such as molds, yeasts, bacteria, spores and activated spores. The invention also promotes malting without competition from microorganisms naturally present on the seeds before malting which not only negatively influence the malting process and the quality of the final malt, but also the quality of the products derived from the malted seeds In an important aspect, the invention provides a method for malting barley, sorghum and wheat, and in a very important aspect, barley. In another important aspect, the invention includes the addition of a starter culture, such as spores or activated spores, after the reduction of the microbial load. In the latter aspect, a starter culture, such as activated spores, provides increased enzymatic activity which is enhanced by reducing the microbial level in the seeds prior to the malting process. The increase of enzymatic activity may be due to reduced competition between the starter culture and the natural occurring microorganisms which have been reduced during the treatment, as well as possible changes in the surface properties of the seeds that permit a better adhesion of a starter culture on the seeds. In yet another important aspect, the process contemplates a continuous treating of the seeds prior to the addition of the starter culture and continuation of the malting process.
The method of the invention is unique in that it may be continuous and does not require increased pressures with sealed containers. The seeds are heated with moist heat and moisture on the surface of the seeds. Care should be taken not to over expose the seeds to the moist heat and/or over expose the seeds to moisture prior to heating because the seeds should not be cooked. Over exposing the seeds to moisture prior to heat will hydrate the seeds below the surface of the seeds and then the moist heat, such as steam, will tend to over heat the seeds, xe2x80x9ccookxe2x80x9d them and reduce their ability to germinate and sprout during the malting process. It is surface moisture on the surface of the seeds coupled with heating which is important in reducing the microbial content of the seeds without substantially adversely affecting the ability of the seeds to germinate and to produce enzymes which are sought through the malting process. Moist heat is applied by a fluid or fluidum which includes heated water or steam having a temperature in the range of about 60xc2x0 C. to about 200xc2x0 C.
The method of the invention will reduce the microbial count of the seeds, such as barley and wheat, by at least about five (5) times per gram of product for molds and 1xc3x97102 per gram for yeasts, and in an important aspect by at least 1xc3x97103 per gram of product for molds and 1xc3x97104 per gram of product for yeasts. Further, the method of the invention is practiced without the necessity of pressurizing the heating vessel to pressures substantially above one atmosphere or atmospheric conditions.
The method includes exposing the seeds to moist heat for a time and temperature that will reduce the microbial count, such as yeast and mold microbes, of the seeds by at least about a factor of five (5) per gram of seed, but will not reduce the germination energy of the seed after about 72 hours to less than about 80%. In general this means that seeds, such as barley and wheat, should be heated with surface moisture on the seeds for from about one to about thirty seconds at a temperature in the range of from about 50xc2x0 C. to about 90xc2x0 C. and preferably from about 60xc2x0 C. to about 90xc2x0 C. Temperature can be conveniently measured by placing a thermometer in the seed bulk. In one important aspect, the seed is a continuously moving stream of seeds. Where it is heated in a moist environment when it is a continuous moving stream, the seeds may be conveyed through a tube-like conduit via paddles where steam having a temperature of from about 100xc2x0 C. to about 200xc2x0 C. is injected through the paddles onto the seeds and increase the moisture content on the seeds. As the seeds go through the conduit, they have steam directly injected onto them which moisturizes and heats the surface of the seeds. The important function of the steam is to provide an amount of surface moisture on the malting seeds which with the heat will kill undesirable microorganisms, but not adversely affect the ability of the seed to sprout and germinate. In this aspect, the steam is effective for heating the seeds to a temperature of at least about 50xc2x0 C., and in an important aspect, heats the seeds from about 60 to about 90xc2x0 C. as they leave the conduit, the seeds residing from about 1 to about 45 seconds, and preferably 3-30 seconds in the conduit. The conduit also may have a heat source (additional to the directly injected steam) which is a jacket which substantially surrounds the conduit throughout its length where the jacket is heated such as by steam, oil, electrically or any other suitable means for heating. The heated jacket indirectly heats the seed.
In another important aspect of the invention where the seeds are treated when continuously moving as a stream, the seeds are conveyed on a pervious belt and has steam having a temperature of from about 100xc2x0 C. to about 200xc2x0 C. injected onto them as they proceed along the belt. In this aspect, the steam is applied to the surface of the seeds which are heated to at least about 50xc2x0 C., and in an important aspect, the seeds are heated to about 65xc2x0 C. to about 85xc2x0 C. as they leave the belt, the seeds residing about 3 to about 30 seconds on the belt.
In another aspect, the seeds may be immersed in water at about 65xc2x0 C. to about 90xc2x0 C. for about 1 to about 20 seconds for good results.
The temperature of the heat source and time of exposure of the seeds to the heat source is a function of the sensitivity of the seeds to heating such that the time and temperature are effective for reducing the microbial count in the seeds by at least about a factor of five per gram of seeds, and the seed does not lose any substantial functionality for the malting process The combination of the temperature of the heat source, steam injection, surface moisture and time of exposure of the seeds to the heat source, however, should be effective to heat the seed to at least 50xc2x0 C. and reduce the yeast and mold count by at least about a factor of five per gram of seed after the seeds are conveyed through the moist heat as described below.
The process of the invention can also include cooling the seeds after heating the seeds with moist heat to cool the seeds down and to ambient temperature. The heating can permit prolonged storage of the seeds with reduced microbial count.